A1.1.1—Water as the medium for life
Water sheltered early life and remains the main cellular medium, enabling dissolved substances to move, react and support temperature control in organisms.
- Syllabus
- First assessment 2025
- Objective
- A1.1.1
- Level
- SL
Exam analysis
Chance of appearing1%of analysed past papers
Latest appearanceNovember 2011
Most common paper—
Typical marks8
Common command terms
- Explain
Scoring notes
- Common mistake
- Describing water only as a habitat without explaining its role as a cellular reaction medium.
Recent exam appearances
November 2011Paper2 SL · TZ06(c)[ 8 ]A1.1.1—Water as the medium for life
Practice this objective
Coverage 2011–2011 · Updated 14 Jul 2026
Concept essentials
- Water provided early life with a stable liquid environment and some protection from ultraviolet radiation.
- Most cellular reactions occur in aqueous solution because dissolved reactants can move and interact.
- Water transports dissolved substances through cytoplasm, blood and plant vascular tissues.
- Hydrogen bonding supports thermal stability and makes evaporation an effective cooling process.